This invention relates to vehicle restraints and, in particular, to devices which hold a truck to a loading dock.
Within the art a number of vehicle restraints have been proposed which act as safety devices to effectively secure a truck in place against the front wall of a loading dock so as to prevent accidental movement of the truck away from the dock while it is being loaded and/or unloaded.
Various techniques of securing the vehicle in place have been utilized. They range from simply chocking the rear wheels of the parked vehicle, the use of chains, or more recently, engaging a mechanical restraint which engages the ICC bar, which is required to be carried on the underside of the vehicle. Each of these techniques has various disadvantages. In the case of vehicle restraints, such fall within two-general categories. A first group are powered and require electrical motors, actuators or hydraulics coupled with electrical controls. Within the patent literature, such electrical or hydraulically operated devices are represented in U.S. Pat. Nos. 4,264,259, 4,282,621, and 4,555,211. These patents are representative of a number of which exist which typify such powered devices. Commercially, they are marketed by Rite-Hite as the ADL Series, by Serco and by Kelley.
A second class of devices are less expensive but usually require a dock attendant to manually engage the lock. The presence of personnel introduces an element of risk to injury during the engaging operation. Such are illustrated, for example, in U.S. Pat. Nos. 4,373,847 and 4,865,508. In some systems, the use of sensors such as a wand, photocells and the like detect the presence of the vehicle ICC bar to initiate action of the motor for purposes of moving the restraint into an operative position. In the case of manual devices, the truck may have to be moved incrementally forward or in reverse to position the ICC bar.
Thus, while the art is replete with a number of techniques and suggestions for vehicles restraints, a need exists for a device which is simple in construction and does not require expensive electrical motors, actuators, hydraulics and the like. Additionally, such a device should preferably be automatically actuated by the truck when the ICC bar has reached a position where it is within the capture range of the device. Moreover, such a device should not require human interaction at the loading dock where there is a high degree of susceptibility to injury.